The meanings of certain acronyms and abbreviations used herein are given in Table 1.
TABLE 1Acronyms and AbbreviationsADAlzheimer's diseaseATPadenosine tri-phosphateBMbone marrowIRinfraredLEDlight-emitting diodeLLLTlow level laser therapyMSCmesenchymal stem cellORTobject recognition testSEMstandard error of the mean
The bone marrow is a complex tissue featuring several different types of primitive cells: hematopoietic stem cells, mesenchymal stem cells (MSCs), endothelial progenitor cells, side population cells, and multipotent adult progenitor cells. Like other stem cells, mesenchymal stem cells are capable of multilineage differentiation from a single cell and in vivo functional reconstitution of injured tissues. One of the properties of stem cells is their capacity to migrate after infusion to one or more appropriate microenvironments. Certain stem cells are able to exit their production site, circulating in the blood before reseeding in their target tissues. For mesenchymal stem cells, the nature of homing sites and circulation into peripheral blood is still under debate. However, mesenchymal stem cells have been found after infusion in multiple tissues, leading to the hypothesis that they can home, and that they adjust their differentiation pathways to diverse tissue microenvironments.